1. Field Of The Invention
The present invention relates to a Chemical Mechanical Polishing (CMP) method for planarizing a semiconductor wafer utilizing a colloidal suspension of an alumina or silica based abrasive and an aqueous trialkanoamine solution.
2. Related Art
Chemical Mechanical Polishing (CMP) is a general procedure used to planarize semiconductor wafers. CMP involves a chemical- mechanical action which changes the surface of the wafer. As shown by Blackwell, U.S. Pat. No. 5,320,706, CMP can involve the use of abrasive particles, such as alumina or silica, which can be used in the form of a slurry, while the wafer is held against a rotating polishing pad. After the wafer has been polished, a post polishing cleaning process can be employed to effect removal of particulate.
Among the various post polishing cleaning methods, there are included intensive mechanical scrubbing procedures which may employ a brush cleaner with deionized water, megasonic cleaning heads, water jet, or chemical bath. However, such procedures often do not provide the conditions required to counteract the electrostatic or Van der Waals forces of the residual particulate.
Control of fine particle adhesion to an object in solution is further shown by Ota et al, U.S. Pat. No. 5,409,544, wherein the zeta- potential of fine particles are investigated. Malik, U.S. Pat. No. 5,078,801 shows a cleaning method for remnant particle removal from a semiconductor wafer after planarization polishing, by placing the wafers in a pH controlled bath.
A cleaning composition capable of removing flux residues from a ceramic substrate is described by Bakos et al, U.S. Pat. No. 4,276,186. Bakos et al. employ a cleaning mixture which includes N-methyl-2-pyrrolidone and an alkanolamine.
While various methods have been used to planarize semiconductor substrates using standard CMP procedures, only those methods providing nearly 100% particulate removal will satisfy the demands of the semiconductor industry. Currently used mechanical intensive scrubbing methods often have been found to be ineffective as a result of a build up of residue in the cleaner during high production periods. In particular instances, such as in the practice of post- tungsten CMP cleaning, where the semiconductor substrate may include tungsten studs recessed in planar SiO.sub.2, slurry particles are often trapped or adhered to the studs.